One major problem in paddy cultivation is control of weeds growing in paddy fields. From ancient times, people spent a lot of time and labor for control of paddy field weeds. However, excellent herbicides have been practically used in recent years, and are largely contributing to labor saving and increased production in paddy cultivation.
At present, in herbicides used for controlling paddy field weeds, various compounds such as bleaching herbicidal active compounds, acetolactate synthase-inhibiting herbicidal active compounds, protoporphyrinogen oxidase-inhibiting herbicidal active compounds, and very-long-chain fatty acid elongase-inhibiting herbicidal active compounds are used as effective components, and there are a number of products. These are usually used by spraying on paddy fields at the same time as transplantation of paddy seedlings, or in the initial phase of the growth of weeds. However, treatment of entire large areas of paddy fields using these herbicides is never easy, and the treatment period overlaps with the busy period of paddy field work. Thus, further labor saving has been demanded.
As a cultivation method for paddy rice other than transplantation cultivation, direct sowing cultivation, in which paddy seeds are directly sown on a paddy field, is carried out. In direct sowing cultivation, the cultivation period in paddy fields is longer than that in transplantation cultivation. Therefore, weeds need to be controlled for a longer period, and there is a problem that spraying of herbicides needs to be carried out a larger number of times.
As methods for saving the labor of control using a pesticide, methods in which seeds before sowing are treated with a pesticide is known. In cases of some microbicides, insecticides, and plant growth regulators, seed treatment agents containing them are now being practically used (Patent Documents 1 to 3)